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By S. N. Monteiro, C. M. F. Vieira, M. M. Ribeiro

"This work has as its objective to evaluate the effect of incorporation of the powder waste retained in the eletrostatic precipitator of the sintering stage from an integrated steel making plant on the physical and mechanical properties of a red ceramic. Formulations were prepared with incorporation of the waste in amounts up to 20 wt.% into a kaolinitic clay. Rectangular specimens were prepared by uniaxial mold-press at 20 MPa and then fired at 750, 900 and 1050°C. The evaluated physical and mechanical properties were: linear shrinkage, water absorption and flexural rupture strength. The results showed that the waste has a potential to be used into red ceramics. The incorporation of the waste enhanced the properties of the ceramic, decreasing the water absorption and increasing the mechanical strength at all investigated temperatures.IntroductionThe sintering stage of an integrated steel-making plant is dedicated to the agglomeration of a mixture of iron ore, coke or coal, fluxes and water [1]. It is a common practice in this stage to use of solid wastes with great amounts of iron in the form of sludge and powder. One of the atmospheric pollutants generated during the sintering process is the particulate material, which is normally retained in an equipment denote as electrostatic precipitator. This equipment retains very small particulates, present in the gaseous emissions by application of an electrical potential difference in between the plates that the fluid is forced to go through. [2]."

Jan 1, 2011

By E. Salinas R.

This work is related with a whole characterization of cantera stone, to establish its characteristics that can give it an additional value for the reuse and reutilization of dust, slurries and small pieces of stone which can be treated as wastes. The obtained results reflects that the residues studied can be used as substitutes of feldspars in the production of pieces of ceramic, and also in the elaboration of paints for the same pieces according to the mixes that can be made with the variation of Na2O, CaO and K2O. According to the humidity proofs and specific gravity done, this material can be proposed as a soil improver into hydroponics systems, leading so an important alternative for food production in zones leaking of water. In the same way, it was found the possibility of use this material as a seal 3A in processes of asphalting of roads, highways and streets.

Jan 1, 2009

By Juan Daniel Martínez, Janaina Accordi Junkes, Dachamir Hotza, Tatiana Pineda

"The rice husk combustion in a bubbling and atmospheric fluidized bed reactor was investigated. The results showed the technical viability of producing both heat and amorphous silica from a renewable energy source. This paper presents the characterization of rice husk ash (RHA) obtained under varying fluidization velocities (0.13-0.15 m/s) and rice husk feed (4.5-7.2 kg/h). Characterization techniques include X-ray fluorescence, X-ray diffraction, particle size distribution and scanning electron microscopy. For the employed range of fluidization velocities of rice husk feed no noticeable influence on the chemical composition of produced RHA was observed. After combustion, RHA containing ~93% amorphous silica and <3% unburned char was obtained. RHA primary particles presented sizes from 90 to 100 µm and a tendency for agglomeration in aqueous media. Thus, the potential of this type of reactors with respect to speed, continuity and self-sufficiency energy of the process was shown.IntroductionDue to the increase of the agroindustrial production, the concern with processing by-products, such as rice husk (RH), is growing. For a better material and energy use, allowing a cleaner production and a more maintainable development, RH can be used as renewable fuel in the production plant, for instance, in steam generators. The adequate combustion of RH generates hot gases with low levels of pollutants, as carbon monoxide and particulate material.RH is the protecting coating formed during the growth of the rice grain, composed by four structural layers.1 The main components of the husk are cellulose and hemicelulose (50%) besides lignine (26%) and organic components (4%), as oils and proteins. The remaining amount includes inorganic materials (SiO2, Al2O3, K2O, Na2O, MgO, CaO, Fe2O3, MnO, P2O5).1The rice husk ash (RHA) is the product of the termochemical transformation of RH. The conditions of the different conversion processes (pyrolysis, gasification and/or combustion) determine the physical-chemical characteristics of the final product. RHA corresponds to 14 to 25% RH, depending on the variety of the rice, climate and soil of the producing area.2-4 The main component of RHA, which is generated at moderate combustion temperatures, is amorphous silica (SiO2) in the range from 80 to 97%.4,5"

Jan 1, 2008

By Hiroyuki Matsuura

The effects of P2OS or Na2O addition on the reaction rate of CO2 dissociation on the surface of FexO-base molten oxides was investigated at I 773K by isotope exchange method 1-6. The rate constant decreased with increasing P2Os content of molten oxides and the residual rate constant was observed at high P2OS content. On the other hand, the rate constant increased with increasing Na20 content for FexO-SiO2 melts, The rate constant was evaluated by the composition of oxides and the rate controlling step of CO2 dissociation was discussed.

Jan 1, 2003

By N. A. Warner

Fundamental studies on the reaction of limestone or dolomite at high temperature with S02 are extended to the realm of large scale primary copper smelting. Whereas flue gas desulfurisation in the electric power utility industry is concerned with S02 concentrations normally less than 0.5 percent, high temperature smelting gases can have S02 levels approaching 100 percent. The reaction involved is very exothermic so proposals are made in this paper for returning the heat generated in sulfur fixation directly back to the copper smelting process. This integration leads to metal production with lower energy requirements than current technology. The anhydrite reaction product can either be disposed of locally with minimum adverse environmental impact or upgraded to a value-added product. It is assumed, of course, that no viable market exists to support sulfuric acid production.

Jan 1, 1996

By Flavio Begazo, William A. Enrico

"Southern Peru Copper Corporation's Ilo Refinery, the largest in Peru, began operations in 1975 with a production capacity of 165,000 stpy. Southern Peru bought the Refinery from the state owned Minero Peru SA on June 1, 1994.The Refinery processes blister from Southern Peru's I/o Smelter. Blister copper is processed in an anode plant equipped with two 365 st tilting reverberatory furnaces, a 26 mold casting wheel and an anode press machine. Copper is electrorefined in a tank house equipped with 768 commercial cells, 44 stripper cells, and 40 liberator cells, utilizing two electrolyte circuits and a 21,000 Ampere rectifier.During 1989 through 1994 a program for improving productivity was carried out by increasing the number of cells and increasing current density to the total rectifier capacity. As a result, a capacity 215,000 stpy of refined copper, 2 million tr. oz silver and 6,000 tr. oz gold per year was achieved. In 1994 Southern Peru announced plans to increase capacity to 250,000 stpy of cathode with a US$ 18 million investment and a US$ 2 million investment in environmental improvement projects, as part of the purchase agreement with the Peruvian government.This paper outlines the scope of the SPCC lio Refinery modernization and environmental program. It describes the implementation of the Electrolytic Plant expansion based on instaliation of polymer concrete cells, a new rectifier, a new selenium roaster and a Precious Metal Plant upgrades."

Jan 1, 1997

By S. V. Cherty

The utilization of natural gas in non-ferrous industries during smelting and refining stages of copper , aluminum, zinc and lead was studied. The total amount of nonelectrical energy consumed in the production of zinc, copper, lead and aluminium, are 96.5% ,93%,92%, and 6 % respectively. It is calculated that 9.45 wt %of air of stoichiometric amount can be substituted by natural gas to the total air input in the nonelectrical energy utilization processes. The results showed that the non electrical energy may be substituted to an amount of 71 % ,52 % ,35 % ,32 % ,and 26% ,in the production of lead, aluminium (plates, foils) copper, aluminium, zinc, respectivelly. Similar calculations are carried out in terms of energy in Btu for the total production of non-ferrous metals in the U.S. It shows that 51.866~106 millions of Btu of nonelectrical energy can be substituted by 54.58~106 cu. ft of natural gas. Finally, the substitution of non electrical energy in terms of equivalent coal energy is discussed. 1t is shown that total non electrical energy is equal to 1.852 million tones of coal .If this 1.852 million tones of coal is replaced by natural gas, a total savings of 22.14 million dollars are achieved. The total or partial substitution of coal by the natural gas in the existing industrial processes and modification of redesigning the processes is discussed.

Jan 1, 1993

By F. A. Myzenkov

The technology developed by the authors uses new methods for raw material smelting in electric furnaces, a new autogenous method and apparatus for subliming smelting for antimony trioxide production and separation of antimony and gold. Concentrate produced from the ore deposits in Yakutia has the following average contents of main constituents, % by weight: 29.4 Sb, 1.2 Fe, 13.1 S, 40.0 SiO2, 0.2 As, 2.6 CaO and 45 g/t of Au. Unlike the technology used abroad a new autogenous method makes it possible to increase considerably specific capacity and reduce gold losses with antimony trioxide by several times. At the same time mineralogical composition of trioxide has improved considerably ? it has mainly a cubic base with prevalence of senarmontite. The content of a main component (Sb2O3) in the final product has increased from 99.0% up to 99.6% which means better quality and makes it suitable for use in special technologies. Despite a lower antimony content of the concentrate (29.4% as compared with over 33% as common in the world practice), an antimony recovery of 85.3% into a commercial-grade product has been achieved, as well as a gold recovery of 96.65% into a gold-antimony alloy. The technology for processing gold-antimony materials developed and introduced at the Ryaztsvetmet plant is unique in the world with respect to gold recoveries.

Jan 1, 2006

By Sharif Jahanshahi

Calcium ferrite slags are often associated with Professor Yazawa due to his pioneering work on the thermodynamics of this type of melts. Over the past years CSIRO has invested some effort in studying physico-chemical properties of such melts to fill in some gaps in our knowledge and explore opportunities for application of the understanding developed. These investigations cover thermodynamics, transport properties of calcium ferrite based slags, as well as the kinetics of reactions of such slags with refractories. The present paper provides an overview of some of these studies and highlights some of the interesting behavior of such melts, The oxidation state of copper and arsenic in calcium ferrite based slags are predominantly Cu+ and As3+, respectively, at oxygen potentials below 10-7 atm. The concentration of CU2+ in such slags becomes significant at oxygen potentials of greater than 10-7 atm at 1300 °C. The activities of CuO0.5 and AsO1.5 in calcium ferrite slags show strong deviations from the Raoultian Law, while that of CoO is very close to ideal behaviour with respect to pure solid CoO. Addition of SiO2 to calcium ferrite slags can have significant effects on the activities of FeO and Fe2O3 and hence the stability of magnetite phase. Transfer of oxygen in calcium ferrite slags is fast with diffusivity of 2x 103 cm2/s at 1350 °C and activation energy of 16 kcal/mol. Presence of solid phases, such as magnetite, has pronounced effect on the viscosity of calcium ferrite slags. The observed dependence on solid loading and shear rate indicates deviation from Newtonian behaviour. The interfacial tension between copper mattes and calcium ferrite slags is strongly dependent on the matte grade, with the determined values being much lower than the corresponding ones for interfacial tension between similar mattes and iron silicate slags. MgO, Cr2O3 and MgCr2O4 have low solubility in calcium ferrite slags and their solubility increases with increasing copper oxide content of the slag at 1300°C. The oxidation state of the slag has strong effects on phase transformation, dissolution rate and disintegration of refractories in calcium ferrite slags. Other key factors with major impact on slag-refractory interactions include viscosity and surface tension of slags as well as the contact angle between slag and refractory material,

Jan 1, 2003

By Jonkion M. Font

An expression for the distribution ratio of arsenic between slag and copper matte or liquid copper was developed by both, an extension of the Reddy-Blander moderl for deriving a priori the arsenic capacity, and by a relationship between the arsenic capacity and the arsenic distribution ratio. In this study, the a priori arsenic capacities in the FeO-SiO2, CaO-SiO2,MgO-SiO2, FeO-CaO-SiO2, FeO1.5-CuO0.5-MgO-SiO2, FeO-FeO1.5-CuO0.5-CaO-Mgo and FeO-FeO1.5-CuO0.5-CaO-Mgo-SiO2, slags were calculated at 1573 K. The a priori arsenic distribution ratio between the FeO-FeO1.5-CuO0.5-CaO-MgO-SiO2 slag and copper matte mn (Lx, )&apos; and between the FeO-FeO1.5-SiO2 or FeO-FeO1.5-CuO0.5*-CaO-Mgo slag and liquid copper (Ls/cua) were calculated. The model calculated data are found to be in good agreement with the reported experimental data. The availability of reliable thermodynamic data for slag components and impurities in the slag-matte- metal system is essential for the accurate prediction of impurity capacities and distribution ratio data. The arsenic distribution ratio model developed here, can be extended for predication in multi-componet slags and mattes or liquid metal, and thereby may lead to the development of new slag systems for the efficient removal of arsenic in the copper smelting, converting and refining processes,

Jan 1, 2003

By Courtney A. Young

Cyanide is a critically important chemical to the mining and metallurgical industry. It has a strong affinity for metals making it favorable as an agent for metal finishing and treatment as well as a lixiviant for metal leaching, particularly gold. These technologies are environmentally sound but, because cyanide is very toxic, safeguards are required to prevent accidental spills and treat effluents before being discharged. Various methods of cyanide remediation by separation and destruction for cyanide management purposes are therefore reviewed. The methods have been broadly categorized as physical, -adsorption. complexation and oxidation methods including photolysis and other advanced-oxidation processes. Reaction mechanisms for these methods are presented throughout this paper, Finally, the methods are compared in regards to their effectiveness in treating various cyanide species: free cyanide, thiocyanate, weak-acid dissociables, and strong-acid dissociables.

Jan 1, 1998

By Orlando C. Gaspar

The textures of the ores, the fine mineral intergrowths, the complex distribution of the deleterious minor elements, and the low base metal contents in some ore types, pose many technological problems to the beneficiation of the volcanogenic massive sulphides occurring in the Iberian Pyrite Belt. In particular fine intergrowths of the base metal sulphides with pyrite impose extremely fine liberation sizes (Kao=15 to 25um). The mineralogical, textural and metallogenic studies have provided an understanding of the distribution of vertical and lateral metal zoning in the ore bodies. Mapping of the ore types, carried out by mine geologists, and the metal zoning patterns computed from data base have shown that ore types are distributed as ore lenses, and that vertical and lateral base metal zoning exists in several orebodies. Since ore processing efficiency is affected by ore textures, and because the same mineral often shows different textural features, a relationship between the textures of the feed ores and those of the middlings must be established for all ore types defined at the deposit scale. For supplying, on time, the information needed for the optimization of the concentration processes, empirical methods of determining the mineralogical and textural characteristics of the several ore types have been developed.

Jan 1, 1995

By Arthur E. Morris

Fifty years ago when Professor Yazawa began his career, the field of process simulation and modeling was in its infancy. Since then, tremendous progress has been made in our ability to model metal production flowsheets from mine to refined metal. This progress has come about by parallel developments in basic understanding of process chemistry and in computational techniques, This paper will review the progress made in process understanding and modeling in lead, zinc, and copper metallurgy from its inception to the present, and the role of Professor Yazawa&apos;s work in furthering this progress. Specific examples will be given for the sintering of lead concentrates, slag fuming, zinc concentrate roasting, flash smelting of copper, and pyro-extraction of zinc. Factors limiting further progress will be described.

Jan 1, 2003

By George S. Dulikravich

An advanced semi-stochastic algorithm for constrained multi-objective optimization has been adapted and combined with experimental testing and verification to determine optimum concentrations of alloying elements in heat-resistant and corrosion-resistant H-Series austenitic stainless steel alloys. The objective was to simultaneously maximize a number of alloy&apos;s mechanical properties. This research will result in a rigorous tool for the design of high-strength H-Series steels and other types of alloys unattainable by any means existing at the present time. Such a material-by-design tool will also be able to reduce or minimize the need for the addition of expensive elements such as Cr, Ni, Co, Nb, Ti, V, etc. and still obtain the optimum properties of an alloy.

Jan 1, 2003

By George S. Dulikravich

An advanced semi-stochastic algorithm for constrained multi-objective optimization has been adapted and combined with experimental testing and verification to determine optimum concentrations of aJ10ying elements in heat-resistant and corrosion-resistant H-Series austenitic stainless steel alloys. The objective was to simultaneously maximize a number of alloy&apos;s mechanical properties. This research will result in a rigorous tool for the design of high-strength H-Series steels and other types of alloys unattainable by any means existing at the present time. Such a material-by-design tool will also be able to reduce or minimize the need for the addition of expensive elements such as Cr, Ni, Co, Nb, Ti, V, etc. and still obtain the optimum properties of an aJ1oy.

Jan 1, 2003

By William A. Hockings

This report describes the results of laboratory studies on leaching of copper ores.tlf These studies are the first step of a program for the investigation of in situ leaching of tabular, metalliferous ore bodies.(2) The basic steps required in the development of an in situ process are: 1. Leachability - the ability to dissolve the metal values from the ore under in situ conditions must be demonstrated. 2. Ore Preparation - the ore must be prepared so that sufficient contact with the solution can be attained. 3. System Design - integrated in situ systems must be designed and studied for engineering feasibility. 4. Economic Feasibility - the economics of the system must be shown to be economically feasible and competitive. 5. Environmental Feasibility - the loss of reagents into the environment must be investigated. 6. Pilot Scale Testing - the feasibility of the system must be demonstrated on a sufficiently large scale. The studies described in this report were concerned only with the first step of the program, viz., leachability. Native and sulfide copper ores from the Michigan copper district were selected as model ores for these studies. Aqueous amnonia solutions were chosen as the solvents to be investigated. In this study carbonate (CO3, HCO3, H2CO3) was used exclusively as the anion. In keeping with custom it is referred to as carbon dioxide and concentrations are ex- pressed in terms of CO2. When leaching native copper the reaction is

Jan 1, 1976

By Atul Kurnar

In the present research a two-cell polymer electrolyte membrane fuel cell stack (PEMFCS) with SS-316 bipolar plates has been tested. Different flow field designs were studied and a modified multi-parallel channel design is proposed. The stack is stable within ±3 mV even after 1000 hours of continuous operation, indicating efficient water management and effective removal of any metal ions from the stack. Also no iron is detected in membrane electrode assembly (MEA) by EDAX analysis after 1000 hours of cell operation. Results indicate that high operating pressures beyond 138 kPa didn&apos;t significantly increase the performance of cell, however added much to the pressurization cost of the system. Tests at different temperatures showed that at temperatures below 80°C, external humidification could be completely removed. The prototype stack is also tested under variable load conditions simulating highway-driving schedule. The experimental efficiency of PEMFCS is 48%, which is in good agreement with the model predicted efficiency of 53.8 %. Results show that 59% of the total losses are due to ohmic polarization in the cell. Further analysis on applications of the stack in automotive transportation system is in progress.

Jan 1, 2002

By Józef Czemecki

Polish copper concentrates are characterized by high levels of impurities, particularly Pb and As. Two technologies are being used for copper concentrate smelting at KGHM Polska Meidz S.A., namely the shaft furnace process (Legnica Copper Smelter, Glogów I Copper Smelter) and a single-stage process for direct to blister concentrate smelting in a flash furnace (Glogów II Copper Smelter). Both technologies are used at different physical and chemical conditions which results, in different impurities behavior. The paper presents flow sheets for copper production in a plant using the shaft furnace process and in another in which a single stage flash process is used. The metals distribution in particular semi-products is given as well as a method for elimination of impurities from the copper production cycle. Methods are also discussed for alloy and matte converting and copper refining to obtain low Pb and As concentrations in anode copper (0.3% Pb and 1500 ppm As maximum) that are being used in the KGHM Polska Meidz plants. Useful co-operation between the plants using different technologies, aimed at the limiting the effect of undesired impurities on the quality of blister copper produced, is also described.

Jan 1, 1998

By Seetharama C. Deevi, Mohammad R. Hajaligol, Sarojini Deevi

"Carbides and nitrides of iron are being considered as magnetic materials for high-density recording due to their chemical stability and high-saturation magnetization values (> 100 emu/g). Iron carbides and iron nitrides with magnetic properties suitable for magnetic media were synthesized by employing a novel synthesis procedure based on fluidization of powders in reactive atmospheres. Fluidized-bed reactors of laboratory, bench, and pilot scale were employed for the synthesis of iron carbide, FeSC2, by reducing and carburizing U-Fe203 in the temperature range of 300 to 550 ºC. A temperature of 400· ºC and a reaction time of 2 to 3 h are found to be optimal for the synthesis of iron carbide. When the carburization was carried out in a reducing and carburizing atmosphere such as carbon monoxide, nucleation and growth of FeSC2 occurred directly from Fe304 with no intermediate phases such as FeO or Fe. Longer carburization times resulted in the deposition of carbon on the surfaces of FeSC2 particles due to Boudouard reaction, and higher temperatures favored the formation of a mixture of carbides such as FesC2 and Fe3C. Iron nitrides were synthesized by reducing u-Fe203 in the temperature range of 350 to 550 ºC, followed by nitriding in the temperature range of 350 to 550·ºC. The powders were characterized using X-ray diffraction, scanning electron microscopy, thermogravimetric analyzer, and a vibrating sample magnetometer.IntroductionRecent demand for high-quality recording of optical, electrical, and audio signals generated interest in magnetic tapes with high-recording densities as compared to the conventional magnetic tapes based on U-Fe203. At present, commercially available magnetic tapes contain maghematite, U-Fe203, as a magnetic material with a saturation magnetization of90 emu/g and a coercive force of 400 Oe. Recording of signals at a higher density per unit volume of magnetic material demands magnetic materials with high-saturation magnetization and a reasonable coercive force. Although metallic iron particles possess a saturation magnetization of 130 to 150 emu/g and a high coercive force of 1000 Oe, the gradual oxidation of iron-to-iron oxides (of lower saturation magnetization) prevents the use of iron particles for high-density recording. In contrast, iron carbides such as FesC2, Fe7C3 and iron nitrides such as Fe4N and Fe3N possess excellent magnetic properties coupled with good electrical conductivities and high hardness. The carbides and nitrides of iron have generated significant interest as magnetic materials for the next generation of magnetic tapes due to their unique magnetic properties and relatively greater oxidation resistance as compared to metallic iron particles [1-4]."

Jan 1, 1994

By Ryszard Prajsnar

During copper production in shaft and flash smelting processes at KGHM Polska Miedz S.A., lead bearing material of sulfide, sulfate, and oxide character is generated in forms such as slime from shaft furnace gas handling systems, converter dusts, and dusts from an electric furnace for copper removal from flash smelting slag. These materials are polymetallic concentrates of Pb, Zn, and Cu, with As, Cl, and Cd as impurities. Shaft furnace slime, containing. about 50% PbS and 15% bituminous substances, is the main lead-bearing material. At the Glogów copper mill, a new plant was commissioned in June 2001 to process 80,000 tonnes per year of lead bearing materials to produce 26,000 tonnes per year of crude lead. The plant consists of a feed conditioning system, three (3) rotary rocking furnaces with a capacity of sixteen (16) tonnes of lead feed fired with natural gas and oxygen-enriched air containing up to 45 vol% O2, and a gas handling system. The gas handling system includes a post-combustion chamber, a gas cooling chamber with Cl neutralization, gas mixing chamber, bag filter, and dry limestone scrubbing system for SO2 removal. The lead-bearing feed is smelted with five (5) wt% Na2CO3 and thirteen (13) wt% iron scrap at a temperature of 950 to 1050°C for three (3) hours. The smelting process consists of four (4) stages; feed drying, firing of gaseous hydrocarbons and solid coal from the feed, lead reduction from slag, and separation of molten products. The flow rates of natural gas and oxygen to the burners are controlled to ensure combustion of the bituminous material in the furnace. The process produces crude lead bullion containing (wt%) 0.1 to 0.5% Cu, 0.02 to 0.5% As, 0.05 to 0.07% Bi, 0.1 to 0.5% Sb, and 0.1 to 0.6%Sn. The process also produces a mixture of sodium silicate slag, Fe-Zn-Pb-Cu-S matte, and Fe-As speiss containing (wt%) 5 to 10% Pb, 2 to 6% Cu, 10 to 15% Zn, 1 to 3% As, 10 to 15% S, 0.5 to 3.0% Cl, 2 to 4% K, 4 to 7% Na, 20 to 30% Fe, and 5 to 10% SiO2. The dust is made up of PbO, ZnO, PbSO4, and PbCI2, KCI, and NaCI with a chemical composition (wt%) of 35 to 50% Pb, 5 to 15% Zn, 3 to 6% As, 4 to 8% Cl, 2 to 5% K, and 2 to 5% Na. The construction of the new lead production plant at the Glogów copper mill will process both current lead-bearing materials as well as lead-bearing material that have been stockpiled over the last fifteen (15) years to give a significant improvement in protection of the natural environment.

Jan 1, 2002